let a = 'aaa'
let b = 123
let c = true
let d = undefined
let e = null
let f = Symbol('f')
let g = BigInt(1223456n)

let obj = {}
let arr = []
let fn = function (){}

console.log(typeof(a))
console.log(typeof(b))
console.log(typeof(c))
console.log(typeof(d))
console.log(typeof(e))    //object
console.log(typeof(f))
console.log(typeof(g))
console.log(typeof(obj))
console.log(typeof(arr))  //object
console.log(typeof(fn))

console.log(obj instanceof Object)
console.log(arr instanceof Array)
console.log(fn instanceof Function)

console.log(Object.prototype.toString.call(a))
console.log(Object.prototype.toString.call(b))

